Food Poisoning Clinical Presentation

Updated: Jun 19, 2018
  • Author: Roberto M Gamarra, MD; Chief Editor: Praveen K Roy, MD, MSc  more...
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A detailed history, including the duration of the disease, characteristics and frequency of bowel movements, and associated abdominal and systemic symptoms, may provide a clue to the underlying cause. The presence of a common source, types of specific food, travel history, and use of antibiotics always should be investigated.

The presenting complaints, typical features and pathogenesis of various causative agents, and diagnosis and treatment information can be found in Table 1 in the Causes section.

The following are some of the salient features of food poisoning:

  • Acute diarrhea in food poisoning usually lasts less than 2 weeks. Diarrhea lasting 2-4 weeks is classified as persistent. Chronic diarrhea is defined by duration of more than 4 weeks.

  • The presence of fever suggests an invasive disease. However, sometimes fever and diarrhea may result from infection outside the GI tract, as in malaria.

  • A stool with blood or mucus indicates invasion of the intestinal or colonic mucosa.

  • When vomiting is the major presenting symptom, suspect Staphylococcus aureus, B cereus, or Norovirus. [1]

  • Reactive arthritis can be seen with Salmonella, Shigella, Campylobacter, and Yersinia infections.

  • A profuse rice-water stool suggests cholera or a similar process.

  • Abdominal pain is most severe in inflammatory processes. Painful abdominal cramps suggest underlying electrolyte loss, as in severe cholera.

  • A history of bloating should raise the suspicion of giardiasis.

  • Yersinia enterocolitis may mimic the symptoms of appendicitis.

  • Proctitis syndrome, seen with shigellosis, is characterized by frequent painful bowel movements containing blood, pus, and mucus. Tenesmus and rectal discomfort are prominent features.

  • Consumption of undercooked meat/poultry is suspicious for Salmonella, Campylobacter, Shiga toxin E coli, and C perfringens.

  • Consumption of raw seafood is suspicious for Norwalk-like virus, Vibrio organism, or hepatitis A.

  • Consumption of homemade canned foods is associated with C botulinum.

  • Consumption of unpasteurized soft cheeses is associated with Listeria, Salmonella, Campylobacter, Shiga toxin E coli, and Yersinia.

  • Consumption of deli meats notoriously is responsible for listeriosis.

  • Consumption of unpasteurized milk or juice is suspicious for Campylobacter, Salmonella, Shiga toxin E coli, and Yersinia.

  • Salmonella has been associated with consumption of raw eggs.



The physical examination should focus on assessing the severity of dehydration and include the following evaluation:

  • A dry mouth, decreased axillary sweat, and decreased urine output indicate mild dehydration, whereas orthostasis, tachycardia, and hypotension indicate more severe volume depletion.

  • A rectal examination always should be performed to directly visualize the stool, to test occult blood, and to palpate the rectal mucosa for any lesions.

  • Rose spot macules on the upper abdomen and hepatosplenomegaly may be seen in Salmonella typhi infection.

  • Erythema nodosum and exudative pharyngitis are suggestive of Yersinia infection.

  • Patients with Vibrio vulnificus or Vibrio alginolyticus may present with cellulitis and otitis media.



The CDC estimates that 97% of all cases of food poisoning result from improper food handling; 79% of cases result from food prepared in commercial or institutional establishments and 21% of cases result from food prepared at home. [7]

The most common causes are as follows: (1) leaving prepared food at temperatures that allow bacterial growth, (2) inadequate cooking or reheating, (3) cross-contamination, and (4) infection in food handlers. Cross-contamination may occur when raw contaminated food comes in contact with other foods, especially cooked foods, through direct contact or indirect contact on food preparation surfaces.

Bacteria are responsible for approximately 75% of the outbreaks of food poisoning and for 80% of the cases with a known cause in the United States. [5] As many as 1 in 10 Americans has diarrhea due to food-borne infection each year.

Table 1.Causes of Food Poisoning. (Open Table in a new window)

Causative Agents

Source and

Clinical Features


Diagnosis and



Improperly stored foods with high salt or sugar content favors growth of staphylococci.

Intense vomiting and watery diarrhea start 1-4 h after ingestion and last as long as 24-48 h

Enterotoxin acts on receptors in the gut that transmit impulses to the medullary centers

Symptomatic treatment

B cereus

Contaminated fried rice (emetic)

Meatballs (diarrheal)

Emetic: Duration is 9 h, vomiting and cramps

Diarrheal: Lasts for 24 h

Mainly vomiting after 1-6 h and mainly diarrhea after 8-16 h after ingestion; lasts as long as 1 d

Emetic enterotoxin (short incubation and duration) - Poorly understood

Diarrheal enterotoxin (long incubation and duration) - Increasing intestinal secretion by activation of adenylate cyclase in intestinal epithelium

Symptomatic treatment

C perfringens

Inadequately cooked meat, poultry, or legumes

Acute onset of abdominal cramps with diarrhea starts 8-24 h after ingestion.

Vomiting is rare. It lasts less than 1 d.

Enteritis necroticans associated with C perfringens type C in improperly cooked pork (40% mortality)

Enterotoxin produced in the gut, and food causes hypersecretion in the small intestine

Culture of clostridia in food and stool

Symptomatic treatment

C botulinum

Canned foods (eg, smoked fish, mushrooms, vegetables, honey)

Descending weakness and paralysis start 1-4 d after ingestion, followed by constipation.

Mortality is high

Toxin absorbed from the gut blocks the release of acetylcholine in the neuromuscular junction

Toxin present in food, serum, and stool.

Respiratory support

Intravenous trivalent antitoxin from CDC

Listeria monocytogenes

Raw and pasteurized milk, soft cheeses, raw vegetables, shrimp

Systemic disease associated with bacteremia

Intestinal symptoms precede systemic disease

Can seed meninges, heart valves, and other organs

Highest mortality among bacterial food poisonings

Highly motile, heat-resistant, gram-positive organism

CSF or blood culture

Must treat with antibiotics if bacteremic

Enterotoxic E coli (eg, traveler's diarrhea)

Contaminated water and food (eg, salad, cheese, meat)

Acute-onset watery diarrhea starts 24-48 h after ingestion

Concomitant vomiting and abdominal cramps may be present. It lasts for 1-2 d

Enterotoxin causes hypersecretion in small and large intestine via guanylate cyclase activation

Supportive treatment

No antibiotics

Enterohemorrhagic E coli (eg, E coli O157:H7)

Improperly cooked hamburger meat and previously spinach

Most common isolate pathogen in bloody diarrhea starts 3-4 d after ingestion

Usually progresses from watery to bloody diarrhea. It lasts for 3-8 d

May be complicated by hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura

Cytotoxin results in endothelial damage and leads to platelet aggregation and microvascular fibrin thrombi

Diagnosis with stool culture

Supportive treatment

No antibiotics

Enteroinvasive E coli

Contaminated imported cheese

Usually watery diarrhea (some may present with dysentery)

Enterotoxin produces secretion

Shigalike toxin facilitates invasion

Supportive treatment

No antibiotics

Enteroaggregative E coli

Implicated in traveler's diarrhea in developing countries

Can cause bloody diarrhea

Bacteria clump on the cell surfaces

Ciprofloxacin may shorten duration and eradicate the organism

V cholera

Contaminated water and food

Large amount of nonbloody diarrhea starts 8-24 h after ingestion. It lasts for 3-5 d

Enterotoxin causes hypersecretion in small intestine

Infective dose usually is 107 -109 organisms

Positive stool culture finding

Prompt replacement of fluids and electrolytes (oral rehydration solution)

Tetracycline (or fluoroquinolones) shortens the duration of symptoms and excretion of Vibrio

V parahaemolyticus

Raw and improperly cooked seafood (ie, mollusks and crustaceans)

Explosive watery diarrhea starts 8-24 h after ingestion

It lasts for 3-5 d

Enterotoxin causes hypersecretion in small intestine

Hemolytic toxin is lethal

Infective dose is usually 107 -109 organisms

Positive stool culture

Prompt replacement of fluids and electrolytes

Sensitive to tetracycline, but unclear role for antibiotics

V vulnificus

Wound infection in salt water or consumption of raw oysters

Can be lethal in patients with liver disease (50% mortality)

Polysaccharide capsule

Growth correlates with availability of iron (especially transferrin saturation >70%)

Culture of characteristic bullous lesions or blood

Immediate antibiotics if suspected (eg, doxycycline and ceftriaxone)

C jejuni

Domestic animals, cattle, chickens

Fecal-oral transmission in humans

Foul-smelling watery diarrhea followed by bloody diarrhea

Abdominal pain and fever also may be present; it starts 1-3 d after exposure and recovery is in 5-8 d

Uncertain about endotoxin production and invasion

Culture in special media at 42°C

Erythromycin for invasive disease (fever)


Potato, egg salad, lettuce, vegetables, milk, ice cream, and water

Abrupt onset of bloody diarrhea, cramps, tenesmus, and fever starts 12-30 h after ingestion.

Usually self-limited in 3-7 d

Organisms invade epithelial cells and produce toxins

Infective dose is 102 -103 organisms

Enterotoxin-mediated diarrhea followed by invasion (dysentery/colitis)

Polymorphonuclear leukocytes (PMNs), blood, and mucus in stool

Positive stool culture

Oral rehydration is mainstay

Trimethoprim-sulfamethoxazole (TMP-SMX) or ampicillin for severe cases

No opiates


Beef, poultry, eggs, and dairy products

Abrupt onset of moderate-to-large amount of diarrhea with low-grade fever; in some cases, bloody diarrhea

Abdominal pain and vomiting also present, beginning 6-48 h after exposure and lasts 7-12 d

Invasion but no toxin production

Positive stool culture finding

Antibiotic for systemic infection


Pets; transmission in humans by fecal-oral route or contaminated milk or ice cream

Acute abdominal pain, diarrhea, and fever (enterocolitis)

Incubation period not known Polyarthritis and erythema nodosum in children

May mimic appendicitis

Gastroenteritis and mesenteric adenitis

Direct invasion and enterotoxin

Polymorphonuclear leukocytes and blood in stool

Positive stool culture finding

No evidence that antibiotics alter the course but may be used in severe infections


Untreated well or spring water

Diarrhea may be bloody

May be chronic up to 42 d in the United States

Enterotoxin, hemolysin, and cytotoxin

Positive stool culture

Fluoroquinolones or TMP/SMX for chronic diarrhea

Parasitic Food Poisoning

Source and Clinical Features


Diagnosis and Treatment

E histolytica

Contaminated food and water

90% asymptomatic

10% dysentery

Minority may develop liver abscesses

Invasion of the mucosa by the parasites

Criterion standard is colonoscopy with biopsy

Ova and parasites may be seen in the stool but has low sensitivity

Luminal amebicides (eg, paromomycin)

Tissue amebicides (eg, metronidazole)

G lamblia

Contaminated ground water

Fecal-oral transmission in humans

Mild diarrhea with nausea and abdominal cramps starts 2-3 d after ingestion; lasts for 1 wk

May become chronic


Highest concentration in the distal duodenum and proximal jejunum

Initial diagnostic test is stool enzyme-linked immunosorbent assay

Duodenal aspiration or small bowel biopsy

Cyst in the stool


Seafood/Shellfish Poisoning

Source and

Clinical Features


Diagnosis and


Paralytic shellfish poisoning

Temperate coastal areas

Source - Bivalve mollusks

Onset usually is 30-60 min

Initial symptoms include perioral and intraoral paresthesia

Other symptoms include paresthesia of the extremities, headache, ataxia, vertigo, cranial nerve palsies, and paralysis of respiratory muscles, resulting in respiratory arrest

Fish acquires toxin-producing dinoflagellates

General observation for 4-6 h

Maintain patent airway.

Administer oxygen, and assist ventilation if necessary

For recent ingestion, charcoal 50-60 g may be helpful

Neurotoxic shellfish poisoning

Coastal Florida

Source - Mollusks

Illness is milder than in paralytic shellfish poisoning

Fish acquires toxin-producing dinoflagellates



Hawaii, Florida, and Caribbean

Source - Carnivorous reef fish

Vomiting, diarrhea, and cramps start 1-6 h after ingestion and last from days to months

Diarrhea may be accompanied by a variety of neurologic symptoms including paresthesia, reversal of hot and cold sensation, vertigo, headache, and autonomic disturbances such as hypotension and bradycardia

Chronic symptoms (eg, fatigue, headache) may be aggravated by caffeine or alcohol

Fish acquires toxin-producing dinoflagellates

Toxin increases intestinal secretion by changing intracellular calcium concentration


Anecdotal reports of successful treatment of neurologic symptoms with mannitol 1 g/kg IV

Tetrodotoxin poisoning


Source - Puffer fish

Onset of symptoms usually is 30-40 min but may be as short as 10 min; it includes lethargy, paresthesia, emesis, ataxia, weakness, and dysphagia; ascending paralysis occurs in severe cases; mortality is high.

Neurotoxin is concentrated in the skin and viscera of puffer fish.



Source - Tuna, mahi-mahi, kingfish

Allergic symptoms such as skin flush, urticaria, bronchospasm, and hypotension usually start within 15-90 min

Improper preservation of large fish results in bacterial degradation of histidine to histamine

Antihistamines (diphenhydramine 25-50 mg IV)

H2 blockers (cimetidine 300 mg IV)

Severe reactions may require subcutaneous epinephrine (0.3-0.5 mL of 1:1000 solution)

Heavy Metal Poisoning





Ingestion of inorganic mercuric salts

Causes metallic taste, salivation, thirst, discoloration and edema of oral mucous membranes, abdominal pain, vomiting, bloody diarrhea, and acute renal failure

Consult a toxicologist

Remove ingested salts by emesis and lavage, and administer activated charcoal and a cathartic

Dimercaprol is useful in acute ingestion


Toxicity results from chronic repeated exposure

It is rare after single ingestion

Common symptoms include colicky abdominal pain, constipation, headache, and irritability

Diagnosis is based on lead level (>10 mcg/dL)

Other than activated charcoal and cathartic, severe toxicity should be treated with antidotes (edetate calcium disodium [EDTA] and dimercaprol).


Ingestion of pesticide and industrial chemicals

Symptoms usually appear within 1 h after ingestion but may be delayed as long as 12 h

Abdominal pain, watery diarrhea, vomiting, skeletal muscle cramps, profound dehydration, and shock may occur

Gastric lavage and activated charcoal

Dimercaprol injection 10% solution in oil (3-5 mg/kg IM q4-6h for 2 d) and oral penicillamine (100 mg/kg/d divided qid for 1 wk)